1. Field of the Invention
This invention relates to a process of manufacturing oriented tapes, which have been folded at least once, from synthetic thermoplastics, particularly for use in the manufacture of high-strength woven fabrics.
2. Description of the Prior Art
So-called container sacks having a large volumetric capacity consist of a woven fabric which has a high tensile strength and has been made from oriented tapes of synthetic thermoplastics. These tapes impart to the woven fabric such a high strength that the contents of the container sacks may have a weight, e.g., in excess of 1000 kg. For even heavier contents, the weight of the woven fabric per square meter must be increased.
The specific tensile strength of the tapes increases as their thickness increases. It is known that the strength of the woven fabric can be increased by an increase of the weight of the woven fabric per square meter by superim posing the tapes, which constitute the filling and warp threads, so that tapes consisting of two plies are obtained. But the manufacture of such two-ply tapes requires more expensive machinery and they can be woven only with difficulty. Other difficulties are due to the fact that it is much more difficult to wind up two-ply tapes than single-ply tapes.